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Dihalomethane
The dihalomethanes are organic compounds in which two hydrogen atoms in methane are replaced by halogen atoms. They belong to the haloalkanes, specifically the subgroup of halomethanes, and contains ten members. There are four members with only one kind of halogen atom: difluoromethane, dichloromethane, dibromomethane and diiodomethane. There are six members with two kinds of halogen atoms: * Bromochloromethane * Bromofluoromethane * Bromoiodomethane * Chlorofluoromethane * Chloroiodomethane * Fluoroiodomethane See also * Monohalomethane * Trihalomethane * Tetrahalomethane Tetrahalomethanes are fully halogenated methane derivatives of general formula CBrkCllFmInAtp, where:k+l+m+n+p=4Tetrahalomethanes are on the border of inorganic and organic chemistry, thus they can be assigned both inorganic and organic names by ... {{Commonscat, Dihalomethanes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure. Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the atmosphere, it is known as atmospheric methane. The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. It has also been detected on other pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bromofluoromethane
Bromofluoromethane is a mixed gaseous halomethane soluble in alcohol and very soluble in chloroform. Its standard molar entropy, ''S''ogas is 276.3 J/(mol K) and heat capacity, ''cp'' is 49.2 J/(mol K). Preparation Up to date, it has been prepared by three prevailingly ineffective methods: # From salts of fluoroacetic acid using a Hunsdiecker type of reaction. # From dibromofluoromethane by reductive debromination with a Swarts reagent. # From a dihalomethane by an halogen exchange reaction or from a halomethane by catalyzed bromination or fluorination. The method with the highest yield is reductive debromination of dibromofluoromethane using an organotin hydride. Uses Bromofluoromethane is an important reagent in the manufacture of intermediates, pharmaceuticals and other chemicals. Usage of bromofluoromethane is regulated due to its ozone depletion potential (0.73). Its isotopomer CH2Br18F contains fluorine-18 (18F) and is used in radiochemistry. Supplier [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trihalomethane
In chemistry, trihalomethanes (THMs) are chemical compounds in which three of the four hydrogen atoms of methane () are replaced by halogen atoms. Many trihalomethanes find uses in industry as solvents or refrigerants. THMs are also environmental pollutants, and many are considered carcinogenic. Trihalomethanes with all the same halogen atoms are called haloforms. Table of common trihalomethanes Industrial uses Only chloroform has significant applications of the haloforms. In the predominant application, chloroform is required for the production of tetrafluoroethylene, precursor to teflon. Chloroform is fluorinated by reaction with hydrogen fluoride to produce chlorodifluoromethane (R-22). Pyrolysis of chlorodifluoromethane (at 550-750 °C) yields TFE, with difluorocarbene as an intermediate. :CHCl3 + 2 HF -> CHClF2 + 2 HCl :2 CHClF2 -> C2F4 + 2 HCl Refrigerants and solvents Trifluoromethane and chlorodifluoromethane are both used as refrigerants. Trihalome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monohalomethane
The monohalomethanes are organic compounds in which a hydrogen atom in methane is replaced by a halogen. They belong to the haloalkanes or to the subgroup of halomethanes. The four members are fluoromethane, chloromethane, bromomethane and iodomethane. See also * Dihalomethane * Trihalomethane * Tetrahalomethane Tetrahalomethanes are fully halogenated methane derivatives of general formula CBrkCllFmInAtp, where:k+l+m+n+p=4Tetrahalomethanes are on the border of inorganic and organic chemistry, thus they can be assigned both inorganic and organic names by ... References {{Commonscat, Monohalomethanes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluoroiodomethane
Fluoroiodomethane is the halomethane with the formula FCH2I. Also classified as a fluoroiodocarbon (FIC), it is a colorless liquid. It is a reagent for the introduction of the fluoromethyl (FCH2) group. Synthesis and uses It is prepared by fluorination of methylene iodide. Its isotopomer 18F">sup>18Fluoroiodomethane is used for fluoromethylation of radiopharmaceuticals Radiopharmaceuticals, or medicinal radiocompounds, are a group of pharmaceutical drugs containing radioactive isotopes. Radiopharmaceuticals can be used as diagnostic and therapeutic agents. Radiopharmaceuticals emit radiation themselves, which is .... Additional reading * * * References Halomethanes Organofluorides Organoiodides {{organohalide-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroiodomethane
Chloroiodomethane is the halomethane with the formula is . It is a colorless liquid of use in organic synthesis. Together with other iodomethanes, chloroiodomethane is produced by some microorganisms. Applications Chloroiodomethane is used in cyclopropanation (''Simmon-Smith reaction''), where it often replaces diiodomethane because of higher yields and selectivity. It is also used in Mannich reaction, aminomethylation, epoxidation, ring opening and addition to terminal alkenes. It is a precursor to chloromethylenating agent Ph3P=CHCl. It reacts with organolithium compounds to give chloromethyllithium (ClCH2Li). Crystallography It crystallizes orthorhombic crystal system with space group ''Pnma'' with lattice constants A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has ...: ''a'' = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorofluoromethane
Chlorofluoromethane or Freon 31 is the hydrochlorofluorocarbon (HCFC) with the formula CH2ClF. It is a colorless, odorless, flammable gas. Uses Pyrolysis of a mixture of dichlorofluoromethane and chlorofluoromethane gives hexafluorobenzene: :3 CHCl2F + 3 CH2ClF → C6F6 + 9 HCl It was used as a refrigerant A refrigerant is a working fluid used in the heat pump and refrigeration cycle, refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Ref ... and has an ozone depletion potential of 0.02. Additional data Its crystal structure is monoclinic with space group P21 and lattice constants ''a'' = 6.7676, ''b'' = 4.1477, ''c'' = 5.0206 (0.10−1 nm), β = 108.205°. At an altitude of 22 km, traces of chlorofluoromethane occur (148 ppt). References External links Thermochemical table at chemnet.ruInfrared Spectrum of Chlorofluoromethane* IARC Summarie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bromoiodomethane
Bromoiodomethane is a halomethane Halomethane compounds are derivatives of methane () with one or more of the hydrogen atoms replaced with halogen atoms ( F, Cl, Br, or I). Halomethanes are both naturally occurring, especially in marine environments, and human-made, most notably ... with the formula BrCH2I. It is a colorless liquid, although older samples appear yellow. The compound has been investigated as a reagent for cyclopropanation by the Simmons-Smith reaction, but diiodomethane and chloroiodomethane are preferred. It also occurs naturally as the result of microbial action. Its critical point is at 367.85 °C and 6.3 MPa and refractive index is 1.6382 (20 °C, D). Additional reading * * * * References External linksUV Spectra data Halomethanes Organobromides Organoiodides {{Organohalide-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bromochloromethane
Bromochloromethane or methylene bromochloride and Halon 1011 is a mixed halomethane. It is a heavy low-viscosity liquid with refractive index 1.4808. Halon 1011 was invented for use in fire extinguishers in Germany during the mid-1940s, in an attempt to create a less toxic, more effective alternative to carbon tetrachloride. This was a concern in aircraft and tanks as carbon tetrachloride produced highly toxic by-products when discharged onto a fire. It was slightly less toxic, and used up until the late 1960s, being officially banned by the NFPA for use in fire extinguishers in 1969, as safer and more effective agents such as halon 1211 and 1301 were developed. Due to its ozone depletion potential its production was banned from January 1, 2002, at the ''Eleventh Meeting of the Parties for the Montreal Protocol on Substances that Deplete the Ozone Layer''. Bromochloromethane's biodegradation is catalyzed by the hydrolase enzyme alkylhalidase: :CH2BrCl + H2O → CH2O + H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halogen
The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group is known as group 17. The word "halogen" means "salt former" (or "salt maker"). When halogens react with metals, they produce a wide range of salts, including calcium fluoride, sodium chloride (common table salt), silver bromide and potassium iodide. The group of halogens is the only periodic table group that contains elements in three of the main states of matter at standard temperature and pressure. All of the halogens form acids when bonded to hydrogen. Most halogens are typically produced from minerals or salts. The middle halogens—chlorine, bromine, and iodine—are often used as disinfectants. Organobromides are the most important class of flame retardants, while elemental halogens are dangerous and can be toxic. Hist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diiodomethane
Diiodomethane or methylene iodide, commonly abbreviated "MI", is an organoiodine compound. Diiodomethane is a colorless liquid; however, it decomposes upon exposure to light liberating iodine, which colours samples brownish. It is slightly soluble in water, but soluble in organic solvents. It has a relatively high refractive index of 1.741, and a surface tension of 0.0508 N·m−1.Website of Krüss'' (8.10.2009) Uses Because of its high density, diiodomethane is used in the determination of the density of mineral and other solid samples. It can also be used as an optical contact liquid, in conjunction with the gemmological refractometer, for determining the refractive index of certain gemstones. Diiodomethane is a reagent for installing the CH2 group. In the Simmons–Smith reaction, it is a source of methylene. In fact the Simmons–Smith reaction does not produce free carbene but proceeds via Zn-CH2I intermediates. Diiodomethane is also a source of the equivalent of CH22 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibromomethane
Preparation Dibromomethane is prepared commercially from dichloromethane via bromochloromethane: :6 CH2Cl2 + 3 Br2 + 2 Al → 6 CH2BrCl + 2 AlCl3 :CH2Cl2 + HBr → CH2BrCl + HCl The latter route requires aluminium trichloride as a catalyst. The bromochloromethane product from either reaction can further react in a similar manner: :6 CH2BrCl + 3 Br2 + 2 Al → 6 CH2Br2 + 2 AlCl3 :CH2BrCl + HBr → CH2Br2 + HCl In the laboratory, it is prepared from bromoform: :CHBr3 + Na3AsO3 + NaOH → CH2Br2 + Na3AsO4 + NaBr using sodium arsenite and sodium hydroxide. Another way is to prepare it from diiodomethane and bromine. Uses Dibromomethane is used as a solvent, gauge fluid, and in organic synthesis (often as 1H-NMR internal standard). It is a convenient agent for converting catechols to their methylenedioxy derivatives. Natural occurrence It is naturally produced by marine algae and liberated to the oceans. Releasing on soil causes it to evaporate and leach into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
